This invention relates to a pump and more particularly to a pump for a reverse circulation rotary drilling rig.
Rotary drilling rigs are commonly used to drill water wells or the like and normally comprise a rotatable Kelly bar having the drilling pipe secured to the lower end thereof. In reverse circulation drilling rigs, the drilling fluid is pumped upwardly through the interior of the pipe string and upwardly through the Kelly bar for subsequent recirculation downwardly through the drill hole outwardly of the pipe string. Conventional reverse circulation drilling rigs employ a primed vacuum system to circulate the drilling fluid upwardly through the drill bit, Kelly bar and Kelly hose. Severe problems are associated with the vacuum systems due to the difficulty in priming and with winter freeze-ups. Further, the priming operation requires considerable time. Applicant has solved the problems normally associated with the conventional reverse circulation systems by mounting a submerged centrifugal pump at the lower end of the Kelly bar. However, the submersion of the pump causes drilling fluid to come into contact with the bearing supporting the pump shaft which greatly reduces the life of the bearing.
Therefore, it is a principal object of the invention to provide a unique pump for a reverse circulation rotary drilling rig.
A further object of the invention is to provide a pump of the type described including means for preventing the drilling fluid from coming into contact with the bearing which supports the pump shaft.
A further object of the invention is to provide a pump including means for fluidly isolating the shaft bearing from the fluid being pumped.
A still further object of the invention is to provide a pump of the type described which is durable in use and easy to service, if necessary.
These and other objects will be apparent to those skilled in the art.